Research On Self-Injection Locking Of Semiconductor Laser Based On Ring Resonator

Semiconductor lasers are small volume and low cost,In the fields of coherent ranging,phased array radar,optical fiber sensing and atomic clock,there is an urgent demand for semiconductor lasers with ultra-narrow linewidth.Using the frequency selection characteristic of the ring resonator,the linewidth of the semiconductor laser can be narrowed and stabilized by self-injection locking.The self-injection narrowing method based on optical fiber ring resonator has the advantages of low cost,simplicity and convenience,and high narrowing efficiency.In this paper,three methods of linewidth measurement of narrow linewidth laser are compared experimentally,and the delayed self-heterodyne method which is suitable for linewidth measurement of(DFB)semiconductor laser with distributed feedback is selected.Based on the transmission characteristics of the ring resonator,a fiber ring resonator close to the critical coupling state is designed,and an experimental device of self-injection locking of semiconductor laser based on fiber ring resonator is built.the linewidth of 1MHz DFB semiconductor laser reaches 6kHz after compression.By comparing the linewidth narrowing and output stability achieved by using fiber ring resonators with different parameters for self-injection locking,the influence of ring resonator structure parameters on semiconductor laser self-injection locking is summarized.In addition,optical fiber ring resonator is easily affected by external environment,such as temperature and vibration,especially the length of optical fiber ring and small free spectrum range,so mode hopping occurs frequently during self-injection locking.Optical waveguide ring resonator has the advantages of compact structure,high integration and strong ability to resist environmental interference,so the research of self-injection locking using optical waveguide ring resonator is carried out at the same time.Using silica optical waveguide ring resonator,the linewidth is 20 kHz after self-injection locking,and the mode hopping stability time is increased to more than 30 minutes.This paper provides a useful reference for self-injection locking using optical fiber and optical waveguide ring resonators.